I have the Coolermaster MH-751 and had the AudioTechnica A990Z (both closed backs) and they were okay. AT 990Z was more detailed but I mean theyre more than 2x the price so not really suprising. However comfort was superb on the MH-751 i have to say.
That said, I recently got the Beyer DT 990 Pro (250 ohm) and in all honesty footsteps in games like Apex Legends, BF1 and BF5 are much more pronounced and sound stage considerably better being open backs. Imaging is top notch. Bass has more punch as compared to the 2 mentioned HPs above and also a bit more pronounced as compared to the DT 880 (250 ohm). If you’re going to use these cans for FPS then i can wholeheartedly recommend them. These would be my main gaming cans until I upgrade to the USD 500 and up range.
As for general music listening, well they do have a bit of peak on treble and in highs in general so being a bit sensitive to highs and treble peaks might dampen you’re music listening experience but Im okay with them so far.
Lastly, you need to get an amp for DT 990 Pro, even the cheaper USD 100 amps/dac combo will work but on board audio or straight from your mobile will not yield a satisfying result.